The objectives of the proposed research are listed below: (1) To produce a total of five billion reference units of human interferon with "Charlie" and to purify human interferon by a procedure which will yield a large amount of purified "Charlie" interferon. (2) To determine the anti-tumor potential of purified "Charlie" interferon by measuring the effect of "Charlie" interferon on the ability of peripheral lymphocytes from blood bank out-dated blood to form colonies in soft agar and to extend this test to lymphocytes from the blood from leukemic humans. (3) To label purified human interferon with radiochemicals of high specific activity so that we would have a biologically active, radioactively-labelled interferon for use as a probe to study the interaction of interferon with the cell surface.